Effigy Mounds National Monument South Unit Trail Map

• Length:  4.5 miles round trip (includes side trip to conical and linear mounds at the southern end of the park)
• Time: 3 hours with time to explore
• Difficulty: Between easy and moderate with a few steep hills

The trails in the South Unit of Effigy Mounds National Monument start on the other side of Highway 76 from the parking lot. There are numerous destinations in the South Unit, but this trail report only covers the hike to the Marching Bear Group starting from the intersection of the main trail through the park and the turnoff for the Compound Mound Group. For details on the hike up to this point, see the Hike to the Compound Mound Group trail report here on National Park Planner.

The hike to the Compound Mound Group intersection is one mile from the trailhead on Highway 76. At this point the trail, a dirt road, is out in the open and heads down a slight but notable hill for the next quarter mile.

Trail south of the Compound Mound Group in the South Unit of Effigy Mounds National Monument

The trail reenters the forest towards the bottom of the hill and then forks. There are no directional signs, so be aware that the fork to the left leads to a few conical and linear mounds. Stay to the right on the dirt road to continue on to the Marching Bear Group.

Forested section of the trail to the Marching Bear Group in the South Unit of Effigy Mounds National Monument

Fork in the trail to the Marching Bear Group in the South Unit of Effigy Mounds National Monument

From the fork, the trail heads uphill all the way to the end, though most of the climb is a gradual ascent. The mounds themselves begin after a quarter mile. The first you will see are on the other side of some thick brush, but you don’t need to bushwhack your way to them. A little farther down is a side trail, so for now just continue straight on the dirt road and take the detour on the way back.

The Marching Bear Group is a string of effigy mounds, which are mounds built in the shape of animals. These types of mounds are only found in northeastern Iowa, southern Wisconsin, northern Illinois, and southeastern Minnesota. Nobody knows their purpose, though archeologists do have various theories: they were used for ceremonial purposes; they marked celestial events; they were territorial markers or boundaries. The only thing known for sure is that they are the newest mounds in this area, having been built between 600 and 1200 AD. While Indians continued to build mounds up until around 1700, the construction of effigy mounds abruptly stopped, like a fad coming to an end.

Types of mounds at Effigy Mounds National Monument

Like all mounds in the park, the Marching Bear mounds have been so whittled down by erosion that they are now barely noticeable. To make visualization easier, the National Park Service mows the grass around the mounds and allows the grass on top of them to grow tall so that the shapes are more defined. Furthermore, the shapes (bears and birds in Effigy Mounds National Monument) are nearly impossible to discern from ground level due to their size. You really need to be up in a tree or flying overhead in a helicopter. Of course that leads to the question as to why the Indians would have gone to all the trouble to build effigy mounds that can only be seen from the sky. The most obvious guess is so that the gods could see them, but since there is no written record, the answer will never be known for sure.

The bear and bird effigy mounds that make up the Marching Bear Group stretch for a quarter mile. Be sure to walk along the mounds on the left side, as that gives you the best perspective on their shapes. Of the five bears and two birds in the group, I was able to get a photograph of one bear and one bird that somewhat captures their shapes. And by the way, archeologists do not know for sure if the effigies are actually bears and birds. They could just as well be bison or bats or any other animal of similar shape (to me, the bird looks like the Batman logo). I have outlined the effigy shapes with a red line in the following photos.

Bear effigy mound in the Marching Bear Group at Effigy Mounds National Monument

Bird effigy mound in the Marching Bear Group at Effigy Mounds National Monument

In my opinion, if you’ve seen one bear and bird mound you’ve seen them all, but for those who disagree, on the way back you can take the side trail to see five more bear effigy mounds, one more bird effigy mound, and a couple of linear mounds (these are the mounds seen earlier through the brush). The linear mounds are at the very end, and unfortunately there is no connector to the main trail at this point—which would make a huge amount of sense—so you must either walk all the way back or Lewis and Clark It™ through the brush to reconnect to the main trail. I had on long pants, so I chose to Lewis and Clark It™. I didn’t pick up any ticks, but I did get plenty of those little sticky burrs that look like steel balls on the end of a chain mace (aka flail).

Linear mound near the Marching Bear Group in the South Unit of Effigy Mounds National Monument

If you still haven’t seen enough Indian mounds, when you get back to where the trail first forked, you can hike to the aforementioned conical and linear mounds. The trail is a narrow grass path, not a dirt road as is the main trail. It is .4 mile long (.8 mile round trip) and downhill all the way on another long and gradual descent. Oddly enough, the soil is similar to beach sand, and even on the grassy sections you can feel your feet sinking slightly into the ground. This is known as loess (pronounced LOW-ess), a sandy soil created when glaciers grind rocks into dust. A loess layer is usually formed when wind blows the dust from one place to another (in the United States, typically from the western plains), but it can also be deposited by glacier melt that carries the silt to the end of a stream or river. The loess layer can be up to 300 feet deep and is actually solid, but it can be easily crumbled like dried mud. It turns to sand on the surface as it is worn down by erosion.

Trail to the conical and linear mounds at the southern end of Effigy Mounds National Monument’s South Unit

The trail map shows three conical mounds a short ways down that veer away from the trail. Any gaps between them were filled in with dirt long ago, so now they just look like a long linear mound. Conical mounds in this area of Iowa date as far back as 2,500 years, and the ones nearest the cliffs overlooking the Mississippi River tend to be the oldest. Linear mounds were built sometime between 300 and 750 AD.

According to the map, the trail forks a little farther down, with a left leading to another group of mounds and a right leading to nowhere. The trail to nowhere is now abandoned and overgrown, so you’ll naturally end up on the trail to the mounds. Furthermore, while the map shows one linear mound and three conical mounds, all there is today are two linear mounds. Like the previous conical mounds, the gaps between them have filled in with dirt. Both mounds are obvious, as they form a waist-high hill in the middle of otherwise flat ground. Even the most unobservant person would realize that these hills are not natural and had to have been made by humans.

Conical mounds now joined together to form a linear mound at the southern end of Effigy Mounds National Monument’s South Unit

At the end of the trail is a view of the Mississippi River, though it is not a good one. Trees and other vegetation now block most of the view.

View of the Mississippi River from the southern end of Effigy Mounds National Monument’s South Unit

When done, head back to the main trail (the gravel road) and take a right to return to the parking lot on Highway 76. Round trip, covering both the Marching Bear Group trail and the trail to the conical and linear mounds is 4.5 miles. If you just hike to the Marching Bears and back, it is 3.7 miles. If you make the side trip to the Compound Mound Group, add another 1.2 mile to the journey.

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